Field
The present invention relates generally to wireless power transfer, and more specifically, to systems, device, and methods for detecting one or more unauthorized devices, one or more near-field communication devices, or a combination thereof, with a charging region of a wireless power transmitter. Furthermore, exemplary embodiments of the present invention relate to systems, device, and methods for limiting wireless power delivery to one or more unauthorized devices, one or more near-field communication devices, or a combination thereof, positioned with a charging region of a wireless power transmitter.
Background
Approaches are being developed that use over the air power transmission between a transmitter and the device to be charged. These generally fall into two categories. One is based on the coupling of plane wave radiation (also called far-field radiation) between a transmit antenna and receive antenna on the device to be charged which collects the radiated power and rectifies it for charging the battery. Antennas are generally of resonant length in order to improve the coupling efficiency. This approach suffers from the fact that the power coupling falls off quickly with distance between the antennas. So charging over reasonable distances (e.g., >1-2 m) becomes difficult. Additionally, since the system radiates plane waves, unintentional radiation can interfere with other systems if not properly controlled through filtering.
Other approaches are based on inductive coupling between a transmit antenna embedded, for example, in a “charging” mat or surface and a receive antenna plus rectifying circuit embedded in the host device to be charged. This approach has the disadvantage that the spacing between transmit and receive antennas must be very close (e.g. mms). Though this approach does have the capability to simultaneously charge multiple devices in the same area, this area is typically small, hence the user must locate the devices to a specific area.
As will be appreciated by a person having ordinary skill in the art, an NFC device, which is operating at the same frequency or capable of picking up power from a wireless power transmitter, may receive excessive power from the wireless power transmitter. Receiving excessive power may result in undesirable heating of the NFC device, which might be a fire hazard. In addition, a rouge receiver may attempt to pick up power from a wireless power transmitter, thus, which may affect power delivery to a valid receiver and, further, may affect efficiency of a wireless power system. A need exists for detection and, possibly, protection of devices within a wireless power system.